1. Field of the Invention
The present invention relates to digital integrated circuitry for comparing sets of data. More specifically, the present invention is a method and apparatus for evaluating asynchronously received sets of data regarding the status of a system and looking for a match in two or more sets of such data.
2. Discussion of Background
Evaluating digital data values is an important function for process control and information management. Comparison of data values is often part of that evaluation. Typically data values are compared bit for bit. Sometimes the comparison is to determine whether the value represented by one set of bits in a data stream has a larger or smaller value than a set of bits in another stream; other systems compare sets of bits to determine if they match exactly. See U.S. Pat. Nos. 4,578,666 issued to Anderson, 4,728,925 issued to Randle, et al., for examples of devices that compare groups or sets of data.
It is sometimes important to know that information received in the form of a set of data is correct, to have confirmation that the condition indicated by the value of the data is in fact correct or at least statistically more likely to be correct than not. It may be that the confirming data may not arrive synchronously with the first data set. It may also be that the data must be processed very quickly for safety reasons, for protecting valuable equipment or for assuring high levels of quality in manufactured products. Circumstances where such a need occurs exist in industrial processes, in secure facilities, in air traffic control, and many other environments.
There is a need for a device that compares asynchronously received data quickly and reliably, and determines from that comparison whether the status of a system has changed in some important way.